One of President Emmanuel Macron's closest advisors announced his resignation, continuing a shake-up of the French leader's inner cabinet as he seeks to claw back lost popularity.

Ismael Emelien, a 31-year-old communications specialist who was an architect of Macron's bid for the presidency, said late Monday that he was leaving to write a book about center-left politics, AFP reported.

He follows another key confidant out of the door of the Elysee palace, speech writer and media advisor Sylvain Fort, after a damaging six-month period for Macron marked by scandal, protests and plummeting approval ratings.

"It's not a resignation, it's a departure," Emelien told AFP, adding that he had always avoided the media while serving as a special advisor to Macron and that his decision to write a book meant he had to resign from his position.

"Any other interpretation of my departure – and there will be others – would be wrong," he added.

Emelien's young age and closeness to Macron saw him build a reputation as one of Paris' most talented political tacticians, who worked behind the scenes providing advice on how to communicate policy choices and counter opponents.

'The battle of ideas'

He was the brains behind Macron's rallying call for action on climate which went viral on social media – "Make our planet great again!" – a response to US President Donald Trump's climate skepticism and catchphrase "Make America great again."

But his powers have been increasingly questioned in recent months, firstly over the handling of a scandal involving Macron's former bodyguard which erupted in July, and later the "yellow vest" protests which began in November.

Since winning the presidency in May 2017, Macron has also been regularly criticized for his aloof style and desire to keep the media at a distance, leading to complaints that he gives few interviews and fails to explain himself enough.

"Ismael is someone who is very committed to the battle of ideas. He wants to lead this fight on the outside in a different way, it's an important fight," government spokesman Benjamin Griveaux told France 2 television, adding that it was a "personal decision".

There have been rumors for weeks that Macron intended to shake up his staff, which has been dominated since his election by the ultra-loyal group of men in their 30s and 40s who became known as the "Macron Boys" during campaigning.

Macron's political advisor Stephane Sejourne has left the presidential team to work on the European Parliament election campaign for Macron's Republic on the Move party, while two other aides, for North Africa affairs and an international media spokeswoman, have also recently departed.

Macron has regained some lost popularity in recent weeks after a series of campaign-style performances at town halls across the country, organized as part of a "great national debate" to discuss the future of the country.

The government organized the debate to defuse the "yellow vest" protests which began over fuel prices but snowballed into a wide and violent challenge to Macron's pro-business tax policies and governing style.